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Re: st: How do I create a calendar year variable by person id before reshaping to person-year dataset?


From   Michael Barker <mdb96statalist@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: How do I create a calendar year variable by person id before reshaping to person-year dataset?
Date   Wed, 5 Feb 2014 12:12:07 -0500

Does the age of the person increase each year?

If so, you could use:
gen year = age+birthyear

If age does not increase each year, how do you know which year an
observation belongs to?
For example, how do you know the records aren't sorted like this:

id     age    sex    birthyear    year
1       5        F       1995        1999
1       5        F       1995        1998
1       5        F       1995        1997
1       5        F       1995        1996
1       5        F       1995        1995


Mike



On Wed, Feb 5, 2014 at 12:03 PM, Holly E Reed <Holly.Reed@qc.cuny.edu> wrote:
> Hi,
>
> I am trying to create a person-year dataset for event history analysis. The dataset currently has one observation per person per year of their life, e.g.:
>
> id     age    sex    birthyear
> 1       5        F       1995
> 1       5        F       1995
> 1       5        F       1995
> 1       5        F       1995
> 1       5        F       1995
> 2       3        M      1997
> 2       3        M      1997
> 2       3        M      1997
>
> So person with id==1 is a 5-year old female born in 1995 and person with id==2 is a 3-year old male born in 1997. This is a simplified example to illustrate the dataset, as they are all adults and there are far more observations for each individual.
>
> The problem is that I have age and birthyear variables, but I want to create a calendar year variable before reshaping the data to person-year data.  What is the easiest way to do this?  In other words, I want the dataset to look like this:
>
> id     age    sex    birthyear    year
> 1       5        F       1995        1995
> 1       5        F       1995        1996
> 1       5        F       1995        1997
> 1       5        F       1995        1998
> 1       5        F       1995        1999
> 2       3        M      1997        1997
> 2       3        M      1997        1998
> 2       3        M      1997        1999
>
> Thank you very much for any help you can give me!
> Holly
>
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